Influence of Homopolymer Addition in Templated Assembly of Cylindrical Block Copolymers.

Templated assembly of cylindrical block copolymers provides a promising strategy for patterning holes at the nanoscale. However, remaining challenges include the ability to achieve defect-free patterns and to generate architectures useful for device patterning. The aim of this work is to gain insight into the influence of homopolymer addition on the assembly of a cylindrical block copolymer in confined space. To do so, a concerted examination that relies on experiments and simulations is carried out for different block copolymer/homopolymer blends. It is shown that by adding a majority block homopolymer with low molecular weight (compared to the blocks that make up the block copolymer), the pattern quality is significantly improved and a larger defect-free window is obtained in terms of template dimensions for two-hole features in elliptical confinements. The redistribution of the homopolymer chains effectively enables the assembly of two cylinders, despite the geometrical mismatch between the elliptical shape of the confinement and the natural hexagonal ordering of the unguided block copolymer. Monte Carlo simulations show that the homopolymer segregates to the spaces in the template that are entropically unfavorable for the block copolymer. This work serves to highlight the importance of optimizing block copolymer formulation.

Forensic studies of brain vulnerability and resistance: ischemia-induced dopamine and serotonin releases in the rat nucleus accumbens.

In this study, we used in vivo brain microdialysis to examine the effects of stimulations of ischemia and/or potassium on the release of dopamine (DA) and serotonin (5-HT) in the nucleus accumbens (ACC) of anesthetized rats. Ischemia (Four-vessels occlusion: 4VO) for 10 min increased DA and 5-HT release in the ACC 200-fold and 15-fold in the first experiment, respectively. In the second experiment, releases of DA and 5-HT in the ACC increased 350-400% and 150-180% by first and second K(+) stimulation, respectively, in the K(+)-K(+) groups. The 4VO treatment induced significant and massive increases of DA and 5-HT releases in the ACC, following K(+) stimulation increased 5-HT release in the Ischemia-K(+) group compared with the K(+)-K(+) group. Also the 4VO treatment in the rotenone (an inhibitor of mitochondorial electric chain)-treated rats showed lower magnitudes of DA and 5-HT massive increases compared with the non-treated control rats in 4VO groups in the third experiment. Different brain vulnerability was shown in the dopaminergic and serotonergic neurons in the same area of the ACC. These findings suggested that the ACC neurons showed a resistance to dysfunction of 10 min-ischemia and maintained neural function, monoamine synthesis and neurotransmitter releases within the transient neural damage, not chronic neural degenerations.

Self-assembly of meta-aminobenzoate on Cu(110).

A variety of structures of meta-aminobenzoate molecules adsorbed on the Cu(110) surface have been characterized by scanning tunneling microscopy (STM) at a wide range of surface coverages, from a single molecule to saturated phases. At the start of molecular domain formation, individual molecules thermally diffuse to form chain structures via intermolecular hydrogen bonding. At higher surface coverages, there coexist three well-ordered phases, namely [Formula: see text] and chiral [Formula: see text] phases. The molecular orientation on the surface also varies with surface coverage. Flat-lying molecules are mainly observed at low surface coverage, while upright molecules start to appear as the surface becomes more highly covered. Our experimental findings and structural analysis are well supported by high-resolution STM images measured at 4.7 K and by molecular packing models with precise lattice parameters.

Reversible control of hydrogenation of a single molecule.

Low-temperature scanning tunneling microscopy was used to selectively break the N-H bond of a methylaminocarbyne (CNHCH3) molecule on a Pt(111) surface at 4.7 kelvin, leaving the C-H bonds intact, to form an adsorbed methylisocyanide molecule (CNCH3). The methylisocyanide product was identified through comparison of its vibrational spectrum with that of directly adsorbed methylisocyanide as measured with inelastic electron tunneling spectroscopy. The CNHCH3 could be regenerated in situ by exposure to hydrogen at room temperature. The combination of tip-induced dehydrogenation with thermodynamically driven hydrogenation allows a completely reversible chemical cycle to be established at the single-molecule level in this system. By tailoring the pulse conditions, irreversible dissociation entailing cleavage of both the C-H and N-H bonds can also be demonstrated.

Acupuncture stimulates the release of serotonin, but not dopamine, in the rat nucleus accumbens.

Acupuncture has been introduced as one of the available therapies widely used in alternative medicine, but it has not achieved widespread acceptance with scientific evidence. Furthermore there are still many unanswered questions about the basic mechanisms of acupuncture. To investigate the neuropharmacological mechanisms of oriental acupuncture, we studied the acupuncture-induced changes of in vivo monoamine release in the rat brain. A microdialysis guide cannula was implanted into the nucleus accumbens (ACC), which plays an important role in the brain reward system. Acupuncture treatment at the unilateral or bilateral Shenshu (bladder urinary channel 23) acupoints, located on the both sides of the spinous processes on the lower back, was carried out for 60 min in freely moving rats, and the dopamine (DA) and serotonin (5-HT) contents of the microdialysates in the ACC were measured simultaneously. In rats subjected to acupuncture at bilateral Shenshu acupoints, increases of 5-HT release in the ACC were observed at 20 min of acupuncture treatment and continued until 40 min after acupuncture was ended. Acupuncture at a unilateral Shenshu acupoint increased the release of 5-HT at 20 min compared with that in the sham-control group. Five-HT release returned to the baseline level at 120 min. The effects of acupuncture at bilateral Shenshu acupoints on the release of 5-HT in the ACC were greater than that of unilateral acupuncture treatment. In contrast, DA release in the ACC was not changed following acupuncture treatment. Effective acupuncture increased and prolonged the activity of serotonergic neurons in the reward system pathway of the brain. This suggests that oriental acupuncture therapy may be effective for the treatment of emotional disorders, drug abuse and alcoholism.

Effects of ethanol on the induction of uncoupling protein-1 (UCP1) mRNA in the mouse brown adipose tissue.

Expression of uncoupling protein-1 (UCP1) is increased by cold acclimation and overfeeding, and reduced in fasting and genetic obesity. It is known that the mitochondrial UCP1 in the brown adipose tissue (BAT) is an important key molecule for non-shivering thermogenesis. On the other hand, ethanol (EtOH) alters thermoregulation in humans and laboratory animals. However, the relationship between EtOH intake and UCP1 expression is not yet clear. Accordingly, the present study employed the technique of real-time quantitative polymerase-chain reaction (PCR) to investigate the effects of EtOH (0.5 or 2.0 g/kg) on the expression of UCP1 mRNA in the mouse BAT. Control mice were injected with the same volume of physiological saline intraperitoneally (IP). IP injection of EtOH (0.5 g/kg) caused a decrease and an increase of the expression of BAT UCP1 mRNA at 1 and 4 hours, respectively. Treatment with EtOH (2.0 g/kg) caused an increases of the expression of BAT UCP1 mRNA at both 2 and 4 hours. BAT UCP1 mRNA levels in both groups increased at 4 hours after EtOH administration. The levels of UCP1 mRNA returned to the control levels by 8 hours after EtOH administration. The expression of BAT UCP1 mRNA was upregulated following EtOH administration, although a lower dose of EtOH initially reduced the expression of UCP1 mRNA in BAT. These findings suggest that EtOH-induced UCP1 mRNA expression in BAT reflects an alteration of the set point of thermogenesis.

Increase of rat alcohol drinking behavior depends on the age of drinking onset.

BACKGROUND: Although alcohol drinking onset in younger people is associated with an increased risk of alcohol-related injuries, other factors, such as habituation and susceptibility to alcohol, in the process of aging have not been adequately examined in animal models. In the present study, we determined whether age of drinking onset affected alcohol drinking behavior and led to alcohol tolerance in experimental animals, and extrapolated some of the findings to human alcohol drinking patterns. METHODS: In the first experiment, 18 rats that were naive to alcohol were tested at the age of 1, 4, and 10 months with 4 hr of access to 10% (v/v) alcohol. After the time access tests, these animals (1, 4, and 10 months of age) were housed individually and given free access to 10% alcohol solution and tap water. At 3 and 6 months later, all rats that had experienced alcohol drinking were studied for the voluntary consumption of the alcohol solution, alcohol preference, under the two-bottle method in a second experiment. RESULTS: In the 4-hr alcohol-access test, alcohol intake (g/kg/hr) was significantly increased at 0.5 and 1 hr in 1- and 4-month-old naive rats compared with 10-month-old naive rats. The daily alcohol intake (g/kg/day) of rats with drinking onset at 1 month of age was significantly increased at 3 and 6 months after the voluntary alcohol consumption. The daily alcohol intake in the rats with drinking onset at 4 months of age was significantly increased at 6 months only. However, the daily alcohol intake did not change in the rats with drinking onset at 10 months of age through the alcohol preference test. CONCLUSIONS: Alcohol drinking behavior in experimental animals depends on the age of alcohol drinking onset.